1. Field of the Invention
The present application relates to power management of computers.
2. Description of the Related Technology
Computers consume electrical energy and reducing energy consumption reduces the costs of running computers. A company may run a very large number of computers. A small saving in energy consumption on each computer results in a large overall saving of energy and thus cost for the company. It is known to monitor activity of a computer and, if an idle state is detected, cause the computer to adopt a low, or lower, power state. That is a well known function within, for example, the Windows™ operating system.
WO 2007/002801 describes a system and method of controlling power in a multi-threaded processor, in particular a processor used in battery powered device such as a mobile telephone, MP3 player or PDA. The activity of threads is monitored and, if all threads are inactive, global resources such as instruction execution units and data and instruction caches, amongst others, are set to a low power state. WO 2007/002801 also describes a development tool, or debug procedure, in which the power states of threads are displayed to detect threads which do not adopt a low power state to enable a programmer to modify the programming so that such threads will, in normal operation, adopt low power states when appropriate to ensure that energy consumption can be reduced.